Manufacture of alkalis.



k. P. McELROY.

MANUFACTURE OF ALKALIS.

APPLICATION FILED JUNE 22. 1915,

Patented Apr. 30, 1918.

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m m mu W To all whom it may concern;

memes.

PATET mI I Ifim KARL P. MQELROY, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR '10 CHEMICAL DEVELOPMENT COMPANY, OF. WASHINGTON, DISTRICT OF COLUMBIA, A CORPORA- 'IION OF MAINE.

MANUFACTURE OF ALKALIS.

tpecification of Letters Patent. Patented Apr. 31), I Ifi'.

Application filed June 22, 1915. Serial No. 35,646.

Be it known that I, KARL P. MCELROY, a citizen of the United States, residing at Washington, in the District of Columbla, have invented certain newand useful Improvements in the Manufacture of 'Alkalis, of which the following is a specification.

This invention relates to the manufacture of alkalis; and it comprises a process of making alkalis and by-products where n a solution of sodium chlorid or potasslum chlorid is electrolyzed for the production of the corresponding alkali and chlorin, and the chlorin is formed or developed on an anode bathed in an atmosphere of gas consisting of or comprising olefins, such gas being advantageously oil gas or a slmilar gas; all as more fully hereinafter set forth and as claimed. 1

In producing alkali by electrolysis of a brine solution the energy required is of course proportional tothe voltage necessary. The voltage between terminals of any cell in actual operation depends upon a number of factors, but in practice is usually 3.5 to 5 volts, the theoretical voltage being around 2.5. One element. is the resistance of the fluid in circuit,- and this is proportional to the thickness of the layer between the poles.

In the present conditions I rearrange the structure of the cell to lessen this thickness of electrolyte layer, and to this end I conusual practice by maintaining an atmosphere I of gases adapted to combine with the chlorin when or as it is formed and to act as anodic depolarizers, thereby reducing the voltage and current consumption required for making alkali. The best gases for this purpose are the gaseous olefins, ethylene and propylene, and the best source is oil gas. Petroleum oils, such as gas oil, crude oil, still residua, etc., on exposure to a temperature of 600 C to 800 0. give gases which are rich in these olefins, ordinar ly running 45 to copper at 250-300 C. or by scrubbing it with a solution of copper nitrate, with a magma of copper hydrate and water, etc. If it is desired to have substantially only ethylene and propylene present, that is if the presence of a little butylene or amylene is not desirable the gas may be scrubbed with chilled oil, or compressed to 60 to 90 pounds and cooled to condense out these bodies. Compressing, chilling and scrub bing with a little cold oil gives a particularly pure gas.

The. olefins on contact with chlorin may react in either of two ways. One is a direct combination with it to form olefin chlorids; bodies in which the olefin is united with 2 atoms, or one molecule, of chlorin. Ethyl ene, (LIL, thus ives ethylene chlorid, or Dutch liquid, ,ILGI a heavy oily body insoluble in water and having an odor and many other properties resembling those of chloroform. The other reaction is one in which water takes part and a chlorhydrin, or chlorinated alcohol, is produced. A molecule of chlorin, C1,, reacts with HOH and C IL to produce HCl and C H OHCI, or a chlorhydrin. Both reactions develop much energy and thereby aid in anodic depolarization.

Both the olefin chlorids and the chlorhydrins are desirable bodies for use in the arts as solvents and for other purposes, though they are wholly different in character. Both are ordinarily produced in the present process though the proportions will vary with In the accom anying illustration, I haveshown a cell un er the present invention and 1 adapted for use in the described process. In

' able material. Between the diaphragms is' upon the conditions.

this showing, a

Figure 1 is a central vertical transverse section;

Fig. 2 is a central longitudinal section along line m-'a,' of Fig. 1.

Fig. 3-is a View in section of a cell arranged for successive treatment of flowing gases; and

Fig. 4 is a perspective view of the same.

In the showing of Figs. 1 and 2 numeral 1 designates as a whole a cell divided into three chambers by two vertical diaphragms, 2 and 3, carrying, respectively, cathode 4: and anode 5. The cell may be constructed of concrete or other suitable material. In the anode chamber the walls and top may be interiorly varnished with a phenolformaldehyde composition to enable'it to resist the action of chlorin and acid. These compositions also withstand the action of olefin chlorids and chlorhydrins fairly well. The cathode may be wire gauze of copper or iron. The anode may be a metallic gauze as well, or it may becarbon or other suita brine chamber 6, provided with brine supply 7 and exit 8. The anode chamber is best constructed (see Fig. 2) as to cause gas passing therethrough to pursue a circuitous or tortuous course in passing from inlet' 9 to outlet 10. This may be provided by alternating depending and upstanding bafile walls 11 and 12, which also serve to support the diaphragm. The diaphragms 12 stop somewhat shortof the bottom of the chamber to afl'ord free liquid communication from end to end. To provide this liquid space, the bottom of the anode chamber may be somewhat depressed, as shown at 13 in Fig. 1.

'In the operation of the cell of Figs. 1 and 2, the alkali forms on the cathode in the usual way and is disposed of as usual. Hydrogen may escape at 14. The chlorin on the other hand develops or tends to develop on the anode and there combines with the olefins of the gas. What results depends With a high current density, chlorin may actually form as gas, at least to some extent, and this gas in mixing with the olefins will form the chlorids;

at leastto some extent. The extent depends exclusion of chlorids.

upon the amount of water vapor present which in turn depends upon the temperature.- With an ample amount of water vapor chlorhydrins may be formed to the 0 Where gas and evolving chlorin come into reaction on the anode itself the tendency is to form chlorhydrins also; this tendency being more marked if there dlaphragm. In general both chlorids and chlorhydrins are formed; but their relative proportions vary with conditions.

is free seepage through the The chlorids being very heavy and insoluble in water tend to separate as an oily layer below the liquid accumulating in the anode chamber. Where chlorhydrins are formed alone they may or may not separate; this depending upon the amount of water in the anode chamber and that of the salt which is in solution therein. The chlorhydrins from oil gas dissolve in about twice their volume of water and to a somewhat less extent in salt solutions. If the amount produced is too great for solution in the accumulating liquid, chlorhydrins will separate as an oily accumulation, sinking if the salt solution is 10 per cent. strong or weaker; and floating if it is saturated. Where the amount of chlorids produced is relatively rather large, the chlorhydrins may be wholly dissolved therein since the olefin chlorids in contact with a water solution of chlorhydrins will extract the greater part of the latter.

Presuming the cell is producing both, the oily layer may be washed with several portions of water to extract the chlorhydrins and the solution so obtained added to the watery liquid withdrawn from the anode chamber. This liquid is next distilled, with or without neutralization to get rid of the hydrochloric acid which is a concomitant of chlorhydrin formation. The chlorhydrins pass over with the first third of the water; and separate generally as oily drops in the first distillate. Using a good column still and returning saturated solution of chlorhydrins distilling over, all the chlorhydrin may be obtained as such by distillation. The oily liquid so obtained may be dehydrated by salt or calcium chlorid, or by redistillation, and is then ready for market. As all the chlorhydrins formed from oil gas have about the same boiling point (the boiling point ranges between 125 and 135 with the dry material), the mixture so obtained behaves for commercial purposes like a unitary body.

The olefin chlorids obtained have a wider range of distillation and it is best to fractionate the product to obtain ethylene and propylene chlorids.

As will be noted in the above operation,

I have cut down the energy required by making the electrolyte layer thinner than is possible where the anode must be inside the cell and by causing the chlorin to combine as it is formed. The amount of energy saved by this anodic depolarization will depend verymuch on the physical conditions in the anode chamber; upon the rate at which the olefins can be brought into reaction with the chlorin. It may range from 10 to 15 per cent. or much higher, as both the heats of formation of olefin chlorids and of the chlorhydrins are heavily exothermic.

As a rule it is better to work cells such as described in a plurality of units arranged in Series as regards passage of gas, that is to feed gas from one cell to another, as this assists 1n good exhaustion and utilization of the contained olefins.

In Figs. 3 and 4 is shown a multiunit cell of somewhat difierent construction as regards the anode chamber, adapted for successive treatment of a current of gas. Casing 20 is spanned by a number of diaphragms to form brine chambers 21, 22, 23, 24 and 25. Anode chambers A and cathode chambers C are arranged in alternation. The cathodes 26 may be wire gauze or netting. As anode material however there is is taken by another cross-pipe 30 to the top of a third anode chamber, whence it emerges at 31.

In the successive chambers it is converted into olefin chlorhydrins or chlorids, or both, in the same manner as in the previous device. The pervious carbon anode massnot only operates as an el'licient mechanical support' for the pair of diaphragms between which it occurs, but also gives a large wetted surface for contact w1th the gas. The arrangement gives a good utilization of the olefins of the gas since the gas may be discharged at 31 practically free of olefins. The device may also be used to give an an proximate separation of the various olefin products since propylene and the higher olefins react more quickly than ethy ene. Using oil gas, the product obtained in the first chamber will contain mainly the propylene butylene and amylene compounds while in the third chamber the products will be mostly ethylene derivatives. In making chlorhydrids for commercial use as a solvent it is better however to reunite these various products since the mixed chlorhydrins' are more desirable.-

In another and copending application, Serial No. 35,505., filed June 22, 1915, I have described and claimed broadly the production of halohydrins or chlorhydrins by electrolysis of a halid or chlorid solution (such; as a solution of common salt,NaCl) in the presence of an olefinic gaasuch as oil gas; but in such other application I describe more specifically the use of the olefins in connection with a liquid bath surrounding the anode and limitation of current density and other conditions to preclude the substantial formation of olefin chlorids. This application contains certaln disclosures occurring in my copending application Ser. No. 712,975 and as regards such matters is a continuation of said application.

What I claim is 1. The process of making alkali and byproducts which comprises electrolyzing a chlorid solution between an anode and a cathode'and duringsuch electrolysis maintaining the anode bathed in a gas comprising an olefin.

2. The process of making alkali. and byproducts which comprises electrolyzing'a chlorid solution between an anode and a cathode and durin such electrolysis main-. taining the anode athed inoil gas.

3. The process of making alkali and byproducts which comprises electrolyzing chlorid solutions in a plurality of cells having anodes and cathodes and during such electrolysis transmitting a current of gas v comprising an olefin successively past the several anodes,

4.. The process of making alkali and byproducts which comprises ing anodes and cathodes and during such electrolysis transmitting a current of oil gas successively past the several anodes.

electrolyzing chlorid solutions in-a plurality of cells hav- 5. The process of making alkali and byproducts which comprises electrolyzing a. thin layer of chlorid solution between a cathode and an anode, said -anode'being separated from said solution by a diaphragm and maintained in an atmosphere of olefinic as.

6. The process of making alkali and yproducts which' comprises electrolyzing a. thin layer of chlorid solution between a cathand maintained in an atmosphere of oil 7. The process of 1 lkali and yproducts which comprises electrolyzing a .ode and an anode, said anode being sepa- .rated from said solution by a diaphragm thin layer of chlorid solution contalned betweena pairof parallel diaphragms separating the .anode and cathode therefrom and during electrolysis maintaining an atmos-' phege of olefinic gas in contact with said ano e. Y

8. The process of making alkali and bytween a'pairot parallel diaphrs sepaproducts which comprises electrolyzing a thin layer of chlorid solution contained bellllh r ting the anode and cathode theretrom and during electrolysis maintaining an atmosphere of oil gas incontact with said anode.

In testimony whereof, T amx my signature.

r. neutron 

